CN116097082A

CN116097082A - Indoor air quality monitor

Info

Publication number: CN116097082A
Application number: CN202180051620.6A
Authority: CN
Inventors: 尼古拉斯·蒙罗; 加布里埃尔·达蒙
Original assignee: Frat Laboratories Ltd
Current assignee: Frat Laboratories Ltd
Priority date: 2020-08-24
Filing date: 2021-08-19
Publication date: 2023-05-09
Anticipated expiration: 2041-08-19
Also published as: EP4200588A2; GB202013185D0; US20230314291A1; CN116097082B; GB2589693A; GB2589693B; WO2022043664A2; WO2022043664A3

Abstract

The present invention provides an indoor air quality monitor (10) having: a housing (12) providing an air inlet (24) leading to an air outlet (28) via a flow path formed within the housing and comprising a flow chamber (70); a fan arranged to push air from the air inlet (24) through the flow path to the air outlet (28); at least one sensor (56, 58, 60, 62) for sensing at least one air contaminant, the sensor (56, 58, 60, 62) being exposed to air in the flow chamber (70); and an air guiding arrangement (46, 48, 64, 66, 74) downstream of the air inlet (24) in the flow path, and the air guiding arrangement (46, 48, 64, 66, 74) forms a plurality of flow channels (76, 78, 80) through each of which air passes to the flow chamber (70) in operation of the indoor air quality monitor.

Description

Indoor air quality monitor

Technical Field

The present invention relates to monitoring of indoor air quality.

Background

Since indoor air quality can have an impact on the health of building occupants and their productivity, indoor air quality is a major concern for building managers, businesses, and even individuals. A wide variety of contaminants are commonly found in building environments that can affect human health and well-being. Reports from the world health organization in 1984 indicate that up to 30% of new and rebuilt buildings may suffer from complaints related to poor air quality. Symptoms believed to be caused by the so-called "sick building syndrome" may include headaches; eye, nose and throat irritation; fatigue and hypodynamia; dizziness and nausea. Poor IAQ can have a significant impact on the productivity of building occupants, but it is also associated with long-term health problems including respiratory disease, heart disease, and cancer.

The pollution level inside the building is generally higher than the pollution level outside the building. Sources of contaminants include fuel burning devices, tobacco products, a range of building and decorative materials, cleaning products and personal care products. Outdoor air pollution may of course also reach the indoor environment. Contaminants in the air within a building may include (a) particulates carried in the air, such as from diesel exhaust, dust and smoke; and (b) Volatile Organic Compounds (VOCs), including formaldehyde, emitted by certain solid and liquid materials common in buildings. Another aspect of IAQ is carbon dioxide concentration. In poorly ventilated buildings, CO in the air exhaled by the occupants of the building ₂ An increase in concentration will significantly increase CO ₂ Concentration in ambient air, while excess air CO ₂ Are believed to have a series of negative effects on human health.

Air humidity can affect the health of building occupants. Too high and too low a humidity are both undesirable.

The air quality within a building may be affected by transient events, such as when a chemical spray is released into the air.

Other aspects of the indoor environment that have an impact on occupant well-being that are not directly related to IAQ include ambient noise and temperature.

The reasons for desiring to monitor IAQ are numerous. Monitoring may enable a series of remedial actions to improve air quality, such as increasing ventilation, or identifying and removing sources of contaminants. By monitoring, the effectiveness of these measures can be determined. Building managers may wish to monitor air quality according to best practices to ensure a healthy environment.

Independent devices for monitoring IAQ are known in the patent literature and are commercially available.

For example, GB2539449 discloses an air quality monitor having a generally annular hollow housing with a sensor mounted on a generally cuboid at the centre of the hollow housing. The device is configured to sense VOCs, CO ₂ And reducing the compound. The device has a fan for exhausting air along an approximate axis of symmetry of the housing, and an air inlet in the side wall. The airflow pattern achieved by this arrangement as the air passes the sensor is not clearly known from the document, but it can be assumed to be somewhat complex and possibly turbulent at different locations.

US2013260668A1 describes a system comprising an air quality "control module", the context of which is control of an HVAC (heating, ventilation and air conditioning) system, but which is configured to compare incoming air from the outside with outgoing stale air to provide a relative measure.

US2017023457A1 relates to a portable ambient air quality monitor in which particulate material is detected by projecting laser light into the air stream and by detecting scattering of the light by aerosol particles, the detection being performed using a photodiode.

Disclosure of Invention

[ technical problem ]

An example of a commercially available IAQ monitor is a Laser Egg (Laser Egg) from Kaiterra (Kaiterra. Com), which is a self-contained disc-shaped device with a display screen on the surface. Numerical simulations performed by one of the inventors have shown that the airflow through the device is far from optimal.

The present inventors have identified three deficiencies in prior art IAQ monitors.

The first of these deficient aspects relates to the management of airflow through the device. The inventors have recognized that existing devices generally have one or more of the following problems:

the air flow through the device is turbulent and/or comprises recirculation zones, which can lead to local variations in the air residence time (thus causing local variations in the residence time of the contaminants carried by the air being sensed). The result may be impaired measurement accuracy and/or increased device response time. That is, poor airflow management can compromise the ability of the device to react quickly to changes in air quality, and as a result transient effects can be missed entirely;

-non-uniform flow. From one point to another, the rate of airflow through the device may vary significantly, which is undesirable in terms of accuracy;

-the chamber volume is excessive. The large volume of the chamber (particularly having a large cross section relative to the flow) increases the time required for the air in the chamber to equilibrate with ambient air, thus increasing the response time of the device.

Poor flow optimization with respect to the sensor. Some sensors operate optimally as the airflow passes over (parallel to) their upper surfaces. This optimal flow pattern is not achieved in many existing devices.

Since IAQ monitors are typically mass-produced products, the cost of their manufacture is important to their commercial success, there is a need to achieve proper airflow management in a simple and economical manner.

A second problem associated with many prior art devices relates to calibration and maintenance. Some sensors require recalibration or replacement to remain accurate for a limited time. There is a need for a means to facilitate this process in a quick and convenient manner for the user. The sensor may also be affected by dust accumulation or contamination.

A third problem relates to the manner in which air quality information is communicated to the user. For example, some known devices are configured to digitally output air quality data to an application running on the mobile device over a WiFi network. It is also known to route data over a wide area network to a remote server that collates and analyzes data from multiple sources. Furthermore, IAQ monitors that carry an electronic display to provide a series of data are also known. However, many occupants of the room are likely to be almost oblivious to the IAQ monitor on a daily basis, and the inventors have realized that in this case a very simple and obvious signalling system is needed to give the user assurance when the air quality is good, and to give an immediate and clear signal when the air quality is poor. This needs to be achieved in a simple manner of manufacture and can provide an aesthetic effect.

Technical scheme

According to a first aspect of the present invention there is provided an indoor air quality monitor comprising:

a housing providing an air inlet opening to an air outlet via a flow path formed within the housing and including a flow chamber;

a fan arranged to push air from the air inlet through the flow path to the air outlet;

at least one sensor for sensing at least one air contaminant, the sensor being exposed to air in the flow chamber; and

an air directing arrangement downstream of the air inlet in the flow path and forming a plurality of flow channels through each of which air passes to the flow chamber in operation of the indoor air quality monitor.

By distributing the airflow between the plurality of flow channels upstream of the flow chamber, the present invention may control the airflow pattern in the flow chamber and may in particular provide a substantially laminar and uniform flow pattern. This makes it possible to reduce the residence time in the flow chamber and correspondingly reduce the time required for the monitor to react to changes in the surrounding contaminant level.

According to a second aspect of the present invention there is provided an indoor air quality monitor ("IAQ monitor") comprising:

a housing providing an air inlet and an air outlet in communication via a flow chamber;

a fan arranged to push air from the air inlet to the air outlet via the flow chamber;

at least one sensor for sensing at least one air contaminant, the sensor being exposed to air in the flow chamber and configured to provide a sensor output indicative of air quality in the flow chamber;

a microprocessor configured to receive and process the sensor output; and

at least one wired or wireless interface device for digitally outputting the sensor data;

wherein the sensor is mounted on a carrier that is removably mounted within the housing such that the carrier can be removed from the housing for replacement, repair and/or calibration of the sensor.

By mounting the sensor on a removable carrier, the present invention provides a sensor that is easily removed from the housing for calibration, repair, and/or replacement.

According to a third aspect of the present invention there is provided an indoor air quality monitor ("IAQ monitor") comprising:

a microprocessor configured to receive and process the sensor output; and

wherein the interior of the housing is divided into by an arrangement of air guides: (a) A first region forming an airflow path from the air inlet to the air outlet, the first region comprising the flow chamber and comprising the at least one sensor; and (b) a second region isolated from the airflow path, the second region comprising the microprocessor and the interface device.

This aspect of the invention provides various advantages by dividing the space within the housing into a region that contains the airflow and includes the sensor, and a separate region that is excluded from the airflow. Protecting potentially sensitive electronic components from contamination by the airflow. Any contamination of the airflow itself by such components is prevented. Thermal effects such as those caused by energy released by active electronic components including microprocessors and wireless interfaces, which might otherwise affect the output of certain sensors, are prevented.

According to a fourth aspect of the present invention there is provided an indoor air quality monitor ("IAQ monitor") comprising:

a microprocessor configured to receive and process the sensor output; and

an illuminable signal panel; and

at least one electrically driven light source for illuminating the signal panel, wherein the hue and/or other visible quality of the light emitted by the light source is adjustable by the microprocessor,

the microprocessor is further configured to adjust the quality of the light emitted by the light source according to the classification of the air quality.

The illuminable signal panel may comprise an edge-lit transparent or translucent body of glass or polymeric material and may provide a very simple and efficient means of signaling the air quality to the occupants of the room.

According to a fifth aspect of the present invention there is provided an indoor air quality monitor ("IAQ monitor") comprising:

a sensor unit housing providing an air inlet and an air outlet communicating via a flow chamber;

a microprocessor configured to receive and process the sensor output;

at least one wired or wireless interface device for digitally outputting the sensor data; and

a base unit;

wherein the sensor unit housing and the base unit are configured to be detachably coupled to each other.

The detachable coupling between the sensor unit housing and the base unit may be achieved using magnets.

Drawings

Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows an indoor air quality monitor ("IAQ monitor") embodying the present invention as viewed from the front and side;

FIG. 2 illustrates a housing of an IAQ monitor;

FIG. 3 shows a base portion of a housing and certain components carried thereon, which are exposed by omitting a cover portion of the housing;

FIG. 4 is similar to FIG. 3 but includes a circuit board;

FIG. 5 includes a view of the underside of the housing cover on the left hand side and a view of the housing and its internal components on the right hand side with the top plate of the cover omitted to reveal internal features;

FIG. 6 shows a view of a housing and its internal components similar to that shown in FIG. 5, but further including a set of flow paths created by computer simulation and representing the path of air through the housing;

FIG. 7 shows how the housing is opened to update the sensor components, and shows three different states of the housing;

FIG. 8 is a plan view of the housing with the top plate of the housing omitted to expose the circuit board and other internal components;

FIG. 9 is a view of the entire IAQ monitor and the peripheral unit on which the IAQ monitor is mounted, as seen from the rear and side;

FIG. 10 is a graph showing the rates at which the internal contaminant concentration and the external contaminant concentration in (a) the present IAQ monitor and (b) the prior art device are equalized by the numerical simulation of the present invention;

FIG. 11 is a graph showing the time variation of contaminant concentration in both devices in the event of a change in the environmental concentration of the contaminant; and

fig. 12 depicts another IAQ monitor embodying the present invention.

Detailed Description

Referring to fig. 1, the present embodiment is an IAQ monitor 10 including a housing 12, the housing 12 in this embodiment carrying a pair of illuminable signal panels 14. For aesthetic purposes, the present embodiment generally has the form of a butterfly, wherein the elongated housing 10 represents the body of the object, and the signal panel 14 represents the wings thereof. To increase this effect, in the present embodiment, the housing carries a pair of projections 16 representing an antenna. Of course, the appearance of the IAQ monitor 10 may vary greatly in other embodiments of the invention.

IAQ monitor 10 performs repeated and frequent sampling of the air quality in its environment from multiple aspects and, in this embodiment, outputs the resulting sensor data by any of the following: (a) Non-wired local area networks (including WiFi in this embodiment) and mobile (cellular) telephone networks, but other non-wired forms of communication may also be employed; (b) a wired local area network; and/or (c) a signal panel 14. The sensor data may then be transmitted over a wide area network, which may be the internet.

Although data from multiple IAQ monitors 10 may be consolidated, such as monitoring at multiple locations in a building, and data from those locations sent to a server for analysis and reporting, the IAQ monitors 10 are substantially self-contained in that they include all of the functionality required to sense and report the air quality in their environment.

Turning now to fig. 2, the housing 12 includes a base portion 18 removably coupled to a cover 20, the parting line 22 between these components being shown in the figure. In this embodiment, air is drawn into the housing through side inlet 24 formed by a plurality of small holes in housing side wall 26. In this embodiment, the lateral direction of the air inlet 24 is convenient in terms of packaging, but in other embodiments the air inlet 24 may be differently oriented, particularly the air inlet 24 may face along the length of the housing 12. In this embodiment, air is discharged from the housing 12 through an air outlet 28 formed in the housing end wall 29, and more specifically, through an air outlet 28 formed in a removable closure portion 30 of the end wall 29. The air outlet 28 takes the form of a plurality of small holes in the closure portion 30. Along the side walls 26 (and along their counterparts on opposite sides of the housing, not shown in fig. 2) are elongate channels 31, the elongate channels 31 for receiving an edge of one of the signal panels 14 for mounting the signal panel.

In operation, air is continually forced through the housing 12 (from the air inlet 24 to the air outlet 28) by electrically driving the fan. The term "fan" as used herein refers to any mechanism capable of properly propelling air but does not require any particular form of mechanism, which may or may not include a rotating device such as an impeller or propeller. The fan is not shown in fig. 2. In the present embodiment, the fan is incorporated in the commercial particulate sensing unit 32 shown in fig. 3. A frusto-conical duct 34 directs airflow from the air inlet 24 into the particle sensing unit 32 and air is expelled from the particle sensing unit 32 through an upwardly facing sensor outlet 36.

The particle sensing unit 32 is of a type known to those skilled in the art, which is based on scattering or reflection of emitted light by particles suspended in a gas stream, which will not be described in detail herein. Any particle sensing device may be used as appropriate in other embodiments of the invention.

Fig. 3 shows a pair of posts 37 carried by the housing base portion 18 and integrally formed with the housing base portion 18. As shown in fig. 4, these posts 37 serve to support a circuit board 38.

The circuit board 38 includes two regions that are spatially separated (as shown in fig. 5 b):

i. a first region 40 exposed to the air flow and comprising an on-board sensor for detecting the air quality; and

a

second area

50, 52, 54, which is not affected by the air flow and comprises electronics other than the sensor itself, in which areas a microprocessor 42 and associated memory, a WiFi chip comprising its antenna, and a set of LEDs 44 for illuminating the signal panel 14 are included.

Referring to fig. 5, the extent of the first region is defined by the peripheral air guides 46, 48, with the air flow being restricted from passing therebetween. The first region 40 is located between the peripheral air guides 46, 48 and occupies a central portion of the circuit board 38, extending along a length portion of the circuit board 38. The second region includes an end 50 and also includes two

peripheral portions

52, 54 juxtaposed with the first region to form a generally "U" shape. The

peripheral portions

52, 54 include LEDs 44.

Within the first region, and mounted on the circuit board 38 are:

first chemical sensor 56 and second chemical sensor 58, which are responsive to volatile organic chemicals ("VOCs"). The two sensors are responsive to different chemicals or chemical classes;

-a unit 60 comprising sensors responsive to ambient temperature and relative humidity; and

-CO ₂ a sensor 62 responsive to carbon dioxide concentration.

Fig. 5b includes the peripheral air guides 46, 48 and a pair of intermediate air guides 64, 66 described above, but omits the top plate 68 of the cover 20 of the housing 12. Nevertheless, it should be appreciated that the air guides 46, 48, 64, 66 are carried by the top plate 68 and are integral with the top plate 68, as will be clear from FIG. 5 a. The lower edges of the air guides 46, 48, 64, 66 are placed on the upper surface of the circuit board 38. Thus, the flow chamber 70 is formed in an area defined between (a) the first region of the circuit board 38, (b) the peripheral air guides 46, 48, and (c) the top plate 68. It should be noted that the depth of the flow chamber (measured perpendicular to the circuit board 38) is shallow, which has an advantageous effect. This serves to minimize the cross-sectional area and volume of the flow chamber and thus the residence time in the flow chamber 70 (of the air and its entrained contaminants). This also helps ensure that the flow through the

sensors

56, 58, 60, 62 is in a desired direction parallel to the upper surface of the sensor, which has been shown to maximize its efficiency.

To maintain laminar flow (as opposed to turbulent flow), the flow of air into and through the flow chamber 70 is carefully controlled. The resulting laminar flow pattern is free of localized areas of stagnation or recirculation that would increase the residence time of particulates and contaminants in these areas. To enter the flow chamber 70, the air exiting the particle sensing unit 32 passes upwardly through an opening 72 (see fig. 4) in the circuit board, after which the curved flow channel formed within the tubing arrangement 74 (see fig. 5 b) diverts the flow approximately 90 degrees (about an axis parallel to the length of the housing 12) to be parallel to and across the circuit board. The flow is then diverted by the curved regions of the air guides 46, 48, 64, 66 approximately 90 degrees (about an axis perpendicular to the circuit board 38) to enter the flow chamber 70, move parallel to the direction of the circuit board 38 and travel along the length of the housing 12.

The shape of the air guides 46, 48, 64, 66 has been the subject of an iterative design process to model a variety of designs and simulate the resulting air flow through finite element analysis in order to achieve the designs described herein. It will be noted that the air guides 46, 48, 64, 66 form a plurality of flow channels in the area where air enters the flow chamber 70—in this embodiment, there are three

such channels

76, 78 and 80. Each of these flow channels diverges slightly in the flow direction. The central flow channel 78 diverges more than the

peripheral channels

76 and 80 and therefore has a large cross-section at the opening leading to the flow chamber 70. This is because the air flow rate into the central flow passage 78 is slightly higher than the air flow rate into the

peripheral passages

76, 80. This is compensated for by the divergence of the central passage 78. Each of the three

channels

76, 78, 80 has a curved shape without any discontinuities that would create turbulence.

The results in terms of airflow are shown in fig. 6, where each of the plurality of lines 82 is formed by numerical simulation and represents the path taken by air to move through the

channels

76, 78, 80 and through the flow chamber 70. It can be observed that the flow is highly laminar, without eddies and without observable turbulence. In addition, the simulation shows that the flow is highly uniform, since the gas flow velocity varies little across the width, depth and length of the flow chamber 70. If the air flow is considered as a vector field, the flow vector at any point in the flow chamber is substantially parallel to the flow vector at any other point, i.e. there is a single flow direction and the air moves substantially along a straight line.

Such laminar, uniform airflow through the smaller flow cross-section flow chamber has the important benefit that any contaminant level within the flow chamber 70 can be quickly equalized with the contaminant level in the ambient air. Fig. 10 shows the results of a simulation performed by one of the inventors using (a) the numerical model of the present IAQ monitor 10 (the results of which are represented by line 84) and (b) the numerical model of another IAQ monitor in the current commercial market leader (the results of which form line 86). The horizontal axis represents time in seconds since the introduction of contaminants into the ambient air. The vertical axis represents the ratio of the level of contaminants within the IAQ monitor to the level of contaminants in the ambient air. It can be seen that in the present IAQ monitor 10, the internal contaminant level reached 90% of the external level within 5 seconds, whereas in the bid, the same change took approximately 50 seconds.

Assessment of air quality and its impact on health is related to transient effects of air quality. For example, sprays such as deodorants or cleaning products are released rapidly and disperse or settle fairly rapidly, but still have an important effect. Therefore, it is important to maximize the response rate of the IAQ monitor 10. This point is shown in fig. 11. Here, blocks 88, 90 represent changes in the environmental contaminant level (this example is somewhat simplified, modeling the contaminant level as a pair of square pulses).

Lines

89 and 91 represent the responses of the present IAQ monitor 10 and the bidding device described above, respectively. It will be observed that when the present IAQ monitor 10 accurately detects the peak level of the contaminant, the bidding device gives an erroneous low reading, since its response is too slow to reach a true reading. Thus, the bidding device may give false warranty responses to such transient events.

It has been pointed out above that some air quality sensors need to be updated regularly, or at least need to be checked and recalibrated. For the present IAQ monitor 10, this is provided by enabling the relevant sensors to be easily removed and replaced. As can be certainly appreciated with reference to fig. 8, in this embodiment, the circuit board 38 includes two separate portions: (a) a fixing portion 38a; and (b) a removable portion 38b that forms a sensor module. In this embodiment, the separation line between the fixed portion 38a and the removable portion 38b corresponds to the aforementioned separation line between the first and second regions, such that the portion of the circuit board that corresponds to the first region and carries the

sensors

56, 58, 60, 62 can be removed for replacement while the portion of the circuit board that carries the remaining electronics is fixed in place. As shown in fig. 7, the removable circuit board portion 38b (hereinafter referred to as "sensor module 38 b") is accessible by sliding and removing the closure portion 30 of the housing end wall 29 rearwardly. The sensor module 38b can then slide out through the resulting opening in the housing end wall 29. Fig. 8 shows the sensor module 38b partially withdrawn from the housing. The longitudinal edges 92, 94 of the sensor module 38b are received in a slip fit manner in corresponding grooves (not shown) in the peripheral air guides 46, 48 to guide the board to its desired position, and in-

line connectors

96, 98 carried on the sensor module 38b and on the fixed circuit board portion 38a, respectively, are arranged to engage when the sensor module 38b is fully slid back into place for this action to make the necessary electrical connection.

This modular form of construction allows the sensor to be easily removed. The sensor module 38b may then be replaced or recalibrated and reinstalled as appropriate. In practice, a swap procedure may be implemented in which the sensor unit 38b that needs to be recalibrated is swapped for a new or recalibrated unit.

IAQ monitor 10 is typically wall-mounted and for this purpose, fig. 9 shows a threaded fastener 100 extending through base portion 18 of the housing (the head of which is covered and hidden by assembly of cover 20 of the housing once the fastener has been screwed into base portion 38 to secure the monitor to the wall). However, fig. 9 also shows an optional backpack unit 102 providing PoE (Power over Electrical wiring, wire-powered) connection to a local area network that may be used in preference to or in addition to wireless LAN. Here powered by mains electricity through cable 104, although in other embodiments IAQ monitor 10 may have an on-board battery that may provide continuous operation in the event of a limited duration power interruption.

The sensor data is typically processed through LAN output and provided to the user through a suitable dashboard, which may be implemented by an application running on the mobile device and/or on a more practical computer system, which may be the same system used to manage other aspects of building management. The data will also typically be output over a wide area network (which may be the internet) to a remote server where the data from the multiple sites is consolidated. These servers may be run by or for the provider of IAQ monitor 10, e.g., the company is thus able to sort and analyze data from multiple sites on which its products are installed. Such batch data may provide valuable insight regarding indoor air quality and impact factors. The data itself may also be of commercial value.

However, this embodiment also provides a very simple and visual indication of the apparent air quality through the signal panel 14 described above. These panels are illuminated in operation by LEDs 44 in an "edge lit" manner. This effect is well known: the light is directed to the panel edge and the panel appears to be luminescent due to the propagation of some internal reflection at the panel surface through the panel. In this embodiment, the signal panel 14 comprises acrylic, which is well suited for such "edge lighting" effects. Each LED includes a plurality of light emitting junctions operating at different wavelengths so that the color of the signal panel 14 can be varied under the control of the on-board microprocessor 42. In this embodiment, the microprocessor is programmed to simply analyze the sensor output data and adjust the light provided to the signal panel 14 accordingly. In particular, the microprocessor may be programmed to select between three states: (a) Good air quality, indicated by green light from the display panel 14; (b) medium air quality, indicated by amber light; and (c) poor air quality, indicated by red light. The display panel provides a clear and immediate signal of the current local air quality to the occupants of the room, and a clear signal for taking remedial action if the air quality is poor.

In addition to detecting indoor air quality, the present embodiment is capable of detecting other aspects of the indoor environment that affect its occupants. In particular, it has a microphone and a light sensor that are responsive to ambient noise. The microphone may be a MEMs type device, although a variety of different microphone technologies may be employed. The light sensor may be a single device or may include multiple sensors responsive to different frequencies. For example, independent measurements of UVa, UVB, infrared and visible light intensities may be provided.

Fig. 12 depicts an IAQ monitor 10a as a further embodiment of the present invention and has many similarities to the above-described embodiments. Which differs from the previous embodiments in that it includes a base unit 150 and a sensor unit 152 that are configured to be coupled to each other but separable. The sensor unit 152 can be removed from the base unit 150 and sent for servicing, which may include calibration and testing of the sensor, for example. The sensor unit 152 includes a sensor and may be similar to the previous embodiments specifically described in fig. 3 to 7 with respect to its installation and management of air flow. In this example, the base unit 150 is wall-mounted and carries the display panel 14, and one or more ports for connection to a power source (and, in some embodiments, to its wired computer network). In the present embodiment, power to operate the sensor unit 152 is transmitted from the base unit 150 to the sensor unit 152 by electromagnetic wireless power transmission, which is a technology that has been widely adopted for wireless charging of mobile phones. In the illustrated embodiment, the power transmitter is wholly or partially received in a stub 154 formed on the base unit 150, and the sensor unit 152 has a complementary recess (not shown in fig. 12) to receive the stub 154 when the two units are coupled. The power receiver is disposed near a recess in the sensor unit 152. Other embodiments may use conventional electrical connectors arranged to mate when the two

units

150, 152 are coupled together for transferring power and/or data therebetween. In the illustrated embodiment, the base unit 150 carries magnets 156, while the sensor unit 152 carries complementarily arranged magnets (these magnets are not shown in the figures) so that when the two units are brought together, the magnetic attraction is used to detachably couple them. Thus, the removal of the sensor unit 152 is very straightforward—the user simply withdraws it from the base unit 150 with sufficient force to overcome the magnet.

Claims

1. An indoor air quality monitor comprising:

2. The indoor air quality monitor of claim 1, wherein each of the flow channels has a cross-sectional area that increases in the direction of airflow.

3. The indoor air quality monitor of claim 1 or 2, wherein two peripheral channels are provided on opposite sides of at least one central channel, and wherein the central channel has a larger cross-sectional area at its downstream end than the individual cross-sectional areas of each of the peripheral channels at its downstream end.

4. The indoor air quality monitor of claim 2, wherein each of the flow channels is curved to change the airflow direction.

5. The indoor air quality monitor of claim 4, wherein the flow channel changes the airflow direction by approximately 90 degrees.

6. An indoor air quality monitor, wherein the sensor is disposed on a circuit board and the flow chamber is defined between:

the circuit board;

a housing panel; and

a pair of peripheral air guides extending between the circuit board and the housing panel.

7. An indoor air quality monitor, wherein the circuit board has a first face and a second face, wherein the first face carries the sensor and is positioned towards the flow chamber, and wherein the flow channel is configured to output air into the flow chamber in a direction substantially parallel to the first face.

8. The indoor air quality monitor of claim 7, wherein the flow path leads through an opening in the circuit board, downstream of which each of the flow channels is curved to divert the air in a direction substantially parallel to a first face of the circuit board.

9. The indoor air quality monitor of any one of claims 6 to 8, comprising two or more intermediate air guides, each of the intermediate air guides being disposed between the peripheral air guides and extending between the circuit board and the housing panel such that each of the flow channels is formed between a pair of intermediate air guides or between an intermediate air guide and a peripheral air guide.

10. The indoor air quality monitor of any of claims 6-9, wherein each of the peripheral air guide and the intermediate air guide is carried by the housing panel.

11. The indoor air quality monitor of any one of claims 6 to 10, wherein the depth of the flow chamber perpendicular to the circuit board is less than 10mm.

12. An indoor air quality monitor as claimed in any preceding claim, wherein the airflow through the flow chamber is substantially laminar.

13. An indoor air quality monitor according to any preceding claim comprising at least one VOC sensor.

14. An indoor air quality monitor ("IAQ monitor"), comprising:

a housing providing an air inlet and an air outlet communicating via a flow chamber;

a microprocessor configured to receive and process the sensor output; and

15. The indoor air quality monitor of claim 14, wherein the carrier includes a first electrical connector and the housing includes a complementary second electrical connector, the first and second electrical connectors being arranged to be connected to one another by the carrier being mounted in the housing to form an electrical connection to the sensor.

16. The indoor air quality monitor of claim 14 or 15, wherein the housing is configured to house the carrier in a slip fit manner.

17. The indoor air quality monitor of claim 16, wherein the carrier is a circuit board and the housing provides a pair of channels for receiving respective edges of the circuit board to form a slip fit.

18. The indoor air quality monitor of claim 17, wherein the flow chamber is defined between:

the circuit board;

a housing panel; and

a pair of peripheral air guides extending between the circuit board and the housing panel,

and wherein each of the peripheral air guides provides a channel for slidably receiving a respective edge of the circuit board.

19. An indoor air quality monitor according to any one of claims 14 to 18, wherein the housing includes a movable or removable closure portion for providing access to the carrier so that the carrier can be removed from the housing.

20. An indoor air quality monitor ("IAQ monitor"), comprising:

a microprocessor configured to receive and process the sensor output; and

21. An indoor air quality monitor ("IAQ monitor"), comprising:

a microprocessor configured to receive and process the sensor output; and

an illuminable signal panel; and

at least one electrically driven light source for illuminating the signal panel, wherein the hue and/or other visible quality of the light emitted by the light source can be adjusted by the microprocessor,

22. The indoor air quality monitor of claim 21, wherein the signal panel comprises a panel of transparent or translucent material that is edge-lit by the light source.

23. An indoor air quality monitor according to claim 21 or 22, wherein the microprocessor is configured to color the signal panel red to indicate poor air quality and green to indicate good air quality.

24. The indoor air quality monitor of claim 23, wherein the microprocessor is configured to classify the air quality into one of three categories or one of four categories, and cause the light source to illuminate the signal panel in a different respective color for each of the categories.

25. An indoor air quality monitor according to any one of claims 21 to 24, further comprising a wired or wireless data output device for outputting sensor data in digital form.